#include <cassert>
#include <iostream>
#include <vector>

void print( double& v ) {
    std::cout << v << std::endl;
}

template< typename V >
void print( V& v ) {
    for( typename V::iterator i = v.begin(); i != v.end(); ++i ) {
        print( *i );
    }
    std::cout << "--" << std::endl;
}

void init( std::vector< double>& v ) {
    for( std::size_t i = 0; i<4; ++i ) {
        v.push_back( i+1 );
    }
}

template< typename V >
void init( V& v ) {
    for( std::size_t i = 0; i<4; ++i ) {
      v.push_back( typename V::value_type() );
      init( v.back() );
    }
}

void clear( double& v ) {
    v=0.0;
}

template< typename V >
void clear( V& v ) {
    for( typename V::iterator i = v.begin(); i != v.end(); ++i ) {
        clear( *i );
    }
}

void pad( double& v ) {
}

template< typename V >
void pad( V& v ) {
    v.insert( v.begin()+2, 2, v[0] );
    clear( v[2] );
    clear( v[3] );
    for( typename V::iterator i = v.begin(); i != v.end(); ++i ) {
        pad( *i );
    }
}

int main() {

/*    std::vector< double > m_data;*/
    std::vector< std::vector< double > > m_data;
//     std::vector< std::vector< std::vector< double > > > m_data;

    init( m_data );
    print( m_data );
    std::cout << "----" << std::endl;
    pad( m_data );
    print( m_data );

}